1. Field of the Invention
The present invention relates to magnetic head fabrication, and more particularly, to an improved method of manufacturing thin closure magnetic read/write heads.
2. Background Information
Nonvolatile storage media technologies, such as magnetic discs, magnetic tape cartridges, and optical disk cartridges are well known. Data storage technology is continually pushed to increase storage capacity and reliability. Decreased bit dimensions have lead to increased data storage densities in magnetic storage media, such as magnetic tape.
Thus, improvement in magnetic medium data storage capacity is achievable, in part, from improvements in the magnetic head assemblies used for reading and writing data on the magnetic storage media. More data tracks on the magnetic tape are made possible by reducing the feature sizes of read and write elements of the head, such as by using thin-film fabrication techniques, to build the heads.
Magnetic tape is passed transversely along a tape path across a write module and a read module of a head assembly for writing data to and reading data from the tape. A critical aspect for tape recording is the ability to read data while it is being recorded. This so-called read-verify, on read-while-write, mode ensures that data is written correctly. If an error is found, writing may stop or data may be re-written. There is a gap between the write elements of the write module and the read elements of the read module, known as “gap-to-gap distance”. As the tape passes between the write and read modules, the tape can “mistrack”, where data is written to or read from the wrong data track, due to the tape skewing as is passes across the gap between the read and write modules. Reducing the gap-to-gap distance between the read and write modules is known to reduce mistracking and reduce errors in reading and writing data and may afford a greater data transfer rate.
Three module head assemblies are emerging for writing and reading data to the tape to improve data transfer rate and reduce mistracking. Three module head assemblies may include two write modules separated by a read module. In three module head assemblies, the gap distance between the read module and the write module is about half the gap-to-gap distance of two module head assemblies, while the gap between the two write modules is about equal to the gap-to-gap distance of two module head assemblies. The reduced gap-to-gap distance of three module head assemblies reduces data read and write errors due to mistracking and increases performance reliability. To achieve the reduced gap-to-gap distance, a thin closure not found in the prior art is needed.
To reduce the wear of the read/write elements of the read and write modules, closures are bonded to the read and write heads. Bonding a relatively thin closure to the heads of the write modules also ensures proper tape contact on the tape bearing surfaces of the head assembly and reduced wear of the heads.
Prior Art FIG. 1 to FIG. 5 illustrate a method for bonding closures to an array of chips. FIG. 1 illustrates a mini-quad of chips 200 that has been cut from a wafer (not shown). The mini-quad 200 includes two columns, shown generally at 202, with an array of chips 204 in each column 202. Each array 204 comprises several rows 206, with each row 206 comprising a chip 208 and auxiliary circuits 210.
Each chip 208 may comprise several read and write elements or devices (not shown). For example, a chip 208 may comprise 16 read elements or 16 write elements or both and 2 servo elements. A chip 208 may also be referred to in the art as a “wafer chip” or “chip image”. The auxiliary circuits 210 are often referred to in the art as electrical lap guides (ELGs), and are referred to as ELGs hereinafter.
The chips 208 and ELGs 210 are formed on a common substrate in a deposition of metallic and non-metallic layers, to form the mini-quad 200. Patterning of the chips 208 and ELGs 210 is accomplished using processes such as photolithography in combination with etching and lift-off processes, for example. After the chips 208 and ELGs 210 are formed, the mini-quad 200 is cut from the wafer. The mini-quad 200 is about 47 mm in length, with each column 202 about 23 mm in length including both the chips 208 and ELGs 210.
Once the mini-quad 200 is formed, closures are attached to the rows 206. Prior art FIG. 2 shows an array of closures 300 that will be bonded to the mini-quad 200. The array 300 comprises a plurality of strips of closures 302 that extend outwardly from a top portion 304. The array of closures 300 comprises a known substrate material, such as Aluminum oxide Titanium carbide (Al2O3TiC).
Prior art FIG. 3 illustrates how the array 300 is bonded to the mini-quad 200. FIG. 4 depicts the array 300 bonded to the mini-quad 200. The array 300 bonds to the mini-quad 200, such that a closure strip 302 is bonded to each row 206 of the mini-quad 200. The closures 302 are provided to protect the magnetic transducers 208.
Once the array 300 is bonded to the mini-quad 200, the top portion 304 of the closures 302 may be removed prior to slicing the mini-quad 200 into rows 206. Grinding may be used to remove the top portion 304 of the array 300, to expose the closures 302 (shown in FIG. 5). After the top portion 304 is removed, the closures 302 may be lapped to a desired width. As can be appreciated, the closure strips 302 are very thin, less than 500 micrometers thick, and extend the length of the mini-quad 200.
The strips of closures 302 can be subjected to flexure during processing. Due to their length and small dimensions, the closures 302 are mechanically fragile. With thicknesses in the range of about 25 to 50 micrometers anticipated in the future, the closures may be more fragile.
Smaller chip images, known as mini-chiplets, allow more devices to be fabricated per wafer, which increases device per wafer yield and can reduce manufacturing costs. The reduced dimensions of arrays of mini-chiplets necessitates a closure design that is robust enough to withstand fabrication and handling processes.
Thus, it would be advantageous to provide a column that comprises chips of reduced dimensions, yet maintains the dimensions of existing columns to facilitate additional processing of the mini-quad with existing processes. Additionally, it would be advantageous to provide a method of fabricating read/write heads with thin closures.